1. Field of the Invention
The present invention relates to a crystallized glass spacer with a high resistance to progress of destruction, i.e., a high fracture toughness and with an appropriate surface resistivity, a method for its production, and a field emission display (field emission-type display, which will be referred to hereinafter as “FED”).
2. Discussion of Background
An FED is an image display apparatus in which a large number of microscopic electron guns (cold-cathode elements) are arranged for each of pixels, and in which electron beams are emitted from the electron guns toward phosphors to form an image, like a cathode ray tube (Cathode Ray Tube, which will be referred to hereinafter as “CRT”).
Since the FED arranged to independently drive the electron guns in each of the pixels, requires no scanning with an electron beam over a wide angle range unlike the CRT, an image display panel thereof can be made thinner and flatter than the CRT (cf. Patent Document 1, for example). Particularly, the FED is expected to be used as a large-screen flat panel display with a diagonal size of at least about 1000 mm (about 40 inches), which is hardly realized by the CRT.
In the FED, an anode panel with phosphors faces an emitter panel with emitters for emitting electrons, through a plurality of spacers, and the periphery of the anode panel and emitter panel is sealed with a sealing material such as a glass paste (frit paste).
The internal space of the FED, i.e., the space between the anode panel and the emitter panel facing each other is typically in a high vacuum state of 10−3-10−5 Pa, and electrons emitted from an emitter of the emitter panel into the space impinge upon a phosphor of the anode panel to induce electron beam-induced luminescence. As a result, a pixel develops a color to form an image.
The distance between the anode panel and the emitter panel facing each other is typically 1-2 mm, and in order to maintain the distance independently of the pressure difference between the atmospheric pressure and the pressure of the internal space (e.g., 10−3-10−5 Pa), the spacers are interposed between the anode panel and the emitter panel, as described above.
Such spacers are required to have a precise dimensional accuracy, and in cases using glass spacers, there is thus a proposed production method of heating a preform with an appropriate accuracy at a temperature around the glass softening point and drawing it (cf. Patent Document 2, for example). This production method is also called a redraw-forming method, and has an advantage that a large amount of spacers can be continuously formed.
In addition, as the definition of the FED becomes finer, the space for installation of the spacers becomes narrower and thus thinner spacers are desired; therefore a glass material which can be produced by the redraw-forming method becomes more advantageous.
It is disclosed that a composition containing no alkali metal is suitable for glass spacers in order to prevent uneven distribution of mobile ions (cf. Patent Document 3). Furthermore, there are other disclosed spacers with an appropriate electronic conductivity made of a glass material containing a transition metal oxide of the element Fe or V in order to prevent charging due to electrons emitted from the emitters (cf. Patent Document 4).    Patent Document 1: JP-A-7-230776    Patent Document 2: JP-A-2000-203857    Patent Document 3: JP-A-2002-104839    Patent Document 4: JP-A-2003-526187